The Secret to Designing an Intuitive UX

Imagine that you’ve never seen an iPad, but I’ve just handed one to you and told you that you can read books on it. Before you turn on the iPad, before you use it, you have a model in your head of what reading a book on the iPad will be like. You have assumptions about what the book will look like on the screen, what things you will be able to do, and how you will do them—things like turning a page, or using a bookmark. You have a “mental model” of reading a book on the iPad, even if you’ve never done it before.

What that mental model in your head looks and acts like depends on a lot of things

If you’ve used an iPad before, your mental model of reading a book on an iPad will be different than that of someone who has never used one, or doesn’t even know what iPads are. If you’ve been using a Kindle for the past year, then your mental model will be different from someone who has never read a book electronically. And once you get the iPad and read a couple of books on it, whichever mental model you had in your head before will start to change and adjust to reflect your experience.

Mental models have been around for a long time

I’ve been talking about mental models (and their counterparts, conceptual models, which we’ll get to shortly) since the 1980s. I’ve been designing interfaces for software, websites, medical devices, and even microwave ovens for (way too many) years. I always enjoy the challenge of matching what is going on in the users’ brains with the constraints and opportunities of the technology of the day (or year, or decade). Interface environments come and go (e.g., the “green screen” of character based systems, or the blue screen of early graphical user interfaces), but people change more slowly. I find that some of the age-old user interface design concepts are still extremely relevant and important. Mental models and conceptual models are some of my favorite interface design concepts that I believe have passed the test of time.

Just how long?

The first person to talk about mental models was K.J.W. Craik in his 1943 book, The Nature of Explanation. Shortly thereafter, Craik died in a bicycle accident and the concept was dormant for many years, until the 1980s when the term reappeared. In the ’80s, there were two books published with the title Mental Models:

So what is a mental model, then?

There are many definitions for mental models that have been around for at least the last 25 years or so. One of my favorites is from Susan Carey’s 1986 journal article, Cognitive science and science education, which says:

A mental model represents a person’s thought process for how something works (i.e., a person’s understanding of the surrounding world). Mental models are based on incomplete facts, past experiences, and even intuitive perceptions. They help shape actions and behavior, influence what people pay attention to in complicated situations, and define how people approach and solve problems.

What is a mental model in interface design?

In the field of user interface design, a mental model refers to the representation of something—the real world, a device, software, etc.—that the user has in mind. It is a representation of an external reality. Users create mental models very quickly, often before they even use the software or device. Users’ mental models come from their prior experience with similar software or devices, assumptions they have, things they’ve heard others say, and also from their direct experience with the product or device. Mental models are subject to change. Users refer to mental models to predict what the system, software, or product is going to do, or what they should do with it. The best history and definition I’ve found about mental models as they relate to software and usability is a 1999 article by Davidson, Dove, and Weltz titled Mental Models and Usability.